Method of assembling multiple element type electron guns

ABSTRACT

A METHOD OF ASSEMBLYING A MULTIPLE ELEMENT TYPE ELECTRON GUN WHEREIN A NUMBER OF ELECTRON GUN UNITS ARE EACH RESPECTIVELY HELD BY PIVOTALLY SUPPORTED HOLDING MEMBERS WHICH ARE ASSEMBLED TO FORM A POLYGONAL SPACE AROUND A CENTRAL AXIS. CONSEQUENTLY, THE ELECTRON GUN UNITS ARE PRESSED AGAINST AND CONTACTED WITH A SOFTENED INSULATNG SUPPORT MATERIAL WHICH HAS BEEN SET AT THE CENTRAL AXIS. THE MATERIAL IS HARDENED, THEREBY SECURING THE ELECTRODES, AND IS THEN CUT AT A PRESCRIBED POSITION THEREON.

' l=.':b.d9',f9 7l r sHlNlcHl sAwAGATA '3551)033 I l i Mmaob 6F {ASSEMBLINGMULTIPLE ELEMENT TYPE ELEcTRoN Guns original Filed Aug, 23,` 1967 2 Sheets-Sheet 2 United States Patent O U.S. Cl. 29-25.16 9 Claims ABSTRACT OF THE DISCLOSURE A method of assembling a multiple element type electron gun wherein a number of electron gun units are each respectively held by pivotally supported holding members Which are assembled to form a polygonal space around a central axis. Consequently, the electron gun units are pressed against and contacted with a softened insulating support material which has been set at the central axis. The material is hardened, thereby securing the electrodes, and is then cut at a prescribed position thereon.

This is a division of application Ser. No. 662,741, filed Aug. 23, 1967, now abandoned.

This invention relates to multiple element type electron gun assemblies yutilized in cathode ray tubes and the like, and more particularly, to a method of assembling same.

Multiple element type electron gun assemblies now predominantly used in shadow mask type cathode ray tubes have generally the type of construction described below.

Generally, each electron gun unit has a first to fourth grid electrodes which are arranged coaxially on a straight line with predetermined spacing therebetween. Each grid is in the form of a cylinder having a perforation at its center to permit passage of an electron beam.

Three unit electron guns, each constructed as above described are assembled together with their centers positioned at the respective apices of an equilateral triangle, the axes of the electron guns being suitably inclined such that electron beams emitted therefrom cross each other at a predetermined point.

Supporting plates are secured (such as by welding) to the outer periphery of the three unit electron guns, opposite ends of each of the supporting plates being secured by fusion to insulating supporting rods made of glass. The multiple element type electron gun assembly of the construction just described has the following defects.

Since the opposite ends of the supporting plates are fused to insulating supporting rods of glass, the length of one side of an equilateral triangle defined by these glass supporting rods becomes substantially equal to the length of the supporting plate, thus decreasing the mechanical strength.

Since the interior of the equilateral triangle defined by the electron guns is vacant, the electron guns have a tendency to be inwardly under the action of external forces whereby the spacing between respective electrodes may be varied or emitted electron beams would not cross each other at the prescribed position. For these reasons when such an electron gun assembly is utilized in a cathode ray tube for television there would arise such diiculties as degrading electrical characteristics of the tube or noncoincidence of colors of the image.

Further, since glass insulating supporting rods are utilized, the size of the equilateral triangle defined by the three glass rods is larger than that of the equilateral triice angle defined by the three electron gun units. Consequently, it may become difficult to insert the assembly into a cathode ray tube through its neck.

SUMMARY OF THE INVENTION rIn accordance with the present invention, the various difficulties mentioned hereinabove can be substantially eliminated by assembling a multiple element type electron gun structure by holding each of a number of electron gun units by means of a pivotally supported holding member. The holding members are then assembled to form a polygonal space defined by the axes of the electron gun units around a central axis. Consequently, the electron gun units are pressed against and contacted with a softened insulating supporting material which has been set at the central axis. The material is allowed to harden, thereby securing the electrodes, and is then cut as a prescribed position thereon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l shows a side elevation of a structure produced according to this invention;

FIG. 2 is a cross-Sectional view taken along a line I-I in FIG. l; and

FIG. 3 is a side View, partly in section, of an apparatus utilized to assemble the multiple element type electron gun embodying this invention.

As shown in FIGS. l and 2, each of three electron gun units 10 comprises first to fourth grid electrodes 11, 12, 13 and 14 which are successively mounted one upon the other along a common axis with predetermined spacings therebetween, Each of these three electron gun units is provided with a perforation, not shown, at its center to pass an electron beam. The three electron gun units are assembled together around a softened insulating supporting rod 16 to form an equilateral triangle defined by the axes thereof and pressed against the rod. Thus the insulating supporting rod 16 is secured by welding to the peripheries of grid electrodes 11 through 14 of said three electron gun units are secured by fusion through arcuate supporting bands 15, respectively. Further, as shown in FIG. l the insulating supporting rod 16 is suitably tapered or inthe form of an elongated frustum so that electron beams emitted from the three electron gun units may cross each other at a predetermined point.

Electron gun units are assembled together by means of an assembling apparatus as shown in FIG. 3.

As shown in FIG. 3 a rod shaped upright stop 21 is mounted at substantially the center of a base plate 20. Around the stop are provided holding mechanisms 22 for the electron gun units, the number of the former corresponding to the number of the latter. For the sake of simplicity FIG. 3 shows only one holding mechanism 22 positioned at one of the apices of an equilateral triangle defined by three electron gun units as shown in FIGS. r1 and 2.

The holding mechanism 22 is pivotally mounted on an L-shaped support 40 which is secured to the base 20 by means of bolts 41. A substantially C-shaped holding member 23 or frame for the electron gun unit is rotatably mounted on a pivot shaft 42 to be operable by a lever 43. A vertical central rod 44 is supported by a bottom yoke 25 of the clamping member 23, said central rod receiving successive grid electrodes 11, 12, 13 and 14 with suitable spacers 27 interposed between adjacent electrodes. The back of substantially C-shaped supporting members 15 are embedded and fixed in the side walls of these first to fourth grid electrodes 11, 12, 13 and 14, respectively. A screw 26 threaded through the upper yoke 24 of the holding member 23 is urged against the upper end of the central rod 44 to clamp and support the electron gun unit 10.

A heating device 28 is positioned above the upright stop 21 coaxially therewith. The heating device 28 comprises a hollow annular body 29 and a heat insulating cylindrical housing 30l which surrounds the annular body 29. An insulating supporting rod made of glass is inserted in said hollow annular body 29 to be heated by a burner 31 provided on the inner wall of the annular body 29. A mixture of gaseous fuel and air is supplied to the interior of the annular body 29 from a source, not shown, via a pipe 32.

The insulating supporting rod -16 made of glass inserted in the annular body 29 is fed by a feed mechanism 33 located above the housing 30 until it engages the upper end of the stop 21 after being heated and softened by the heating device 218. Then the holding member 23 for the electron gun unit is tilted from a position indicated by dotted lines to a position indicated by solid lines by pushing upwardly the lever 43.

In the latter position the free end of the lower yoke 2S engages the side surface of the stop 21 thus limiting the movement of the holding member 23. As a consequence supporting members of respective grid electrodes 11, 12, 13 and 14 are pressed against the softened glass supporting rod 16 and secured thereto by fusion. Thereafter the supporting rod 16 is cut at a suitable position remote from the head of the stop 21 by means of a suitable automatic cutter 34. Then the screw 26 threaded through the upper yoke of the clamping member 23 is loosened to permit withdrawal of spacers 27 between adjacent grid electrodes in the direction of arrows. Then the central rod 44 is withdrawn from the electron gun unit -10 and thereafter the holding member 23 is tilted back to the original position shown by dotted lines by means of the lever 43. Grid electrodes 11, 12, 13 and 14 fused to the insulating supporting rod 16 are then removed to provide a multiple element type electron gun assembly of the construction shown in FIGS. 1 and 2.

While in the above embodiment a gas burner 31 is used as the heating means it will be understood that a high frequency heating device may also be used. Further, to provide oxidation-free electron gun assemblies, they may be positioned in vacuum or nitrogen atmosphere.

The above described embodiment relates to a three electron gun assembly for use in color cathode ray tubes. Two electron gun assemblies for use in observation cathode ray tubes can also be manufactured by the same process. In this case, a pair of holding members for electron gun units are disposed to oppose each other and a heated and softened insulating supporting rod of glass is fed between opposed holding members and the holding members are assembled to fuse the electron gun units to the softened rod.

Thus, in accordance with this invention no vacant space is left within a polygon formed by a plurality of electron gun units so that the assembled structure has great mechanical strength and there is no fear that the electron gun units may be displaced under external forces towards the axis of the electron gun assembly. As a consequence, in cathode ray tubes employing the novel electron gun assembly there is no fear of degradation of the tube characteristics as well as non-coincidence of images of different colors.

Further, the electron gun assemblies constructed in accordance with this invention are of small size so that they can be readily inserted in relatively narrow necks of cathode ray tubes.

I claim:

1. A method of assembling a multiple element type electron gun structure comprising the steps of:

holding each of a plurality of electron beam emitting electron gun units, each of which includes a plurality of spaced coaxial grid electrodes, by means of a respective pivotally supported holding member;

inserting into said space a softened insulating supporting material;

pivoting each of the holding members to locate said electron gun units about a central axis to form a polygonal space defined by said electron gun units around said central axis;

allowing said material to substantially fill said space and to contact said electrodes and harden, thereby securing said electrodes; and

cutting said insulating supporting material at a prescribed position.

2. A method according to claim 1 wherein said insulating supporting material is an insulating rod.

3. A method according to claim 1 wherein said holding and pivoting steps are performed by:

mounting a plurality of grid electrodes one upon the other along a common axis with predetermined spacing therebetween on a plurality of substantially C-shaped electrode holding members pivotally mounted on a base; and

causing said holding members to revolve to a prescribed position dened by a stop member.

4. A method according to claim 2 wherein a heating means is located above said holding members and wherein said inserting step includes feeding said insulating supporting rod into said polygonal space through said heating means for softening said rod.

5. A method according to claim 2 including the steps of connecting a supporting member to each of said electrodes, said insulating supporting rod thereby being further secured to said electrodes.

6. A method of assembling a multiple element type electron gun structure comprising the steps of:

holding each of a plurality of electron beam emitting electron gun units, each of which includes a plurality of spaced coaxial grid electrodes, by means of a respective pivotally supported holding members;

locating a softened insulating supporting material at a predetermined central axis;

pivoting each of the holding members to locate said electron gun units about said central axis to form a polygonal space defined by said electron gun units around said central axis;

pressing said electron gun units against said softened insulating supporting material; and

allowing said material to harden, thereby securing said electrodes.

7. A method according to claim 6 wherein said softened material is allowed to substantially fill said space prior to hardening thereof.

8. A method according to claim 6 wherein said insulating supporting material is an insulating rod.

9. A method according to claim 8 wherein a heating means is located above said holding members and wherein said inserting step includes feeding said insulating supporting rod into said polygonal space through said heating means for softening said rod.

References Cited UNITED STATES PATENTS 3,085,172, 4/1963 Smith 313-82 3,250,935 5/1966 Johnson 313-70 3,289,268 12/ 1966 De Bernardis 29-25.19 3,340,035 9/1967 Hajduk 29-25.6X 3,363,298 1/'1968 Merchant 29-25.19 3,417,448 12/1968 Kelley 29-25.13 3,434,819 3/1969 Merchant et al. 29-25.16X

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner U.S. Cl. X.R. 

